Method and apparatus for compensating for injection media viscosity in a pressurized drug injection system

ABSTRACT

A needleless injection system is provided to deliver therapeutic fluids to an internal treatment site in a patient, where the system is pressurized and is capable of compensating for differences in injection media viscosity and mechanical system characteristics. In one aspect, a needleless therapeutic fluid injection system is provided that includes modular, interchangeable components. In particular, the system includes a console that generally includes the electronic and/or hydraulic control components for the system, an injection chamber, and a shaft or catheter tube.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority under 35 U.S.C. §119(e) to U.S.Provisional Application No. 61/141,153 (Rykus), filed Dec. 29, 2008,titled “Method and Apparatus for Compensating for Injection MediaViscosity in a Pressurized Drug Injection System”, the entire contentsof which are incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates generally to the delivery of therapeuticfluids to a treatment site within a patient. More specifically, theinvention relates to methods and devices for treating tissue within thehuman body using a pressurized injection system that deliverstherapeutic fluids to a desired location, such as the urinary tract of apatient.

BACKGROUND

A wide variety of medical treatments utilize the delivery andintroduction of therapeutic compositions to a treatment location in apatient. In home or outpatient settings, the delivery methods used caninclude procedures such as oral delivery or inhalants, while in clinicalor hospital types of settings, a therapeutic fluid is often injectedusing a needle-based system. In more complicated methods, a fluid can bedelivered surgically through a tubular device, such as a catheter orendoscope, and in some cases, the surgical method can involve minimallyinvasive procedures.

When liquid medications are administered using methods such as oralmedication administration (i.e., swallowing the medication) or receivingthe medication via a needle-based injection or a drip line, the amountof medication being dispensed is typically easily controllable andverifiable using simple measuring and/or viewing techniques. However,when the fluid is delivered to the patient internally through a tubulardevice, the ability to observe and adjust the medication administrationcan be more difficult. Thus, a number of systems have been developed fordelivering therapeutic fluids to treatment sites within a patient thatinclude minimally invasive, tubular delivery lumens (e.g., catheters orendoscopes) and fluid sources that are actuated by a plunger. Thisplunger can help the user to control the amount of fluid that isdelivered to and/or expelled from the system. In some cases, theminimally invasive fluid delivery systems are not reusable, as the costto sterilize the components can be prohibitive. These systems caninclude needleless fluid injection systems, for example. Needlelessdevices and methods for treating tissue of the urinary tract arediscussed in Applicants' copending application U.S. Patent ApplicationPublication No. 2006/0129125 and U.S. Ser. No. 12/087,231, filed Jun.27, 2008 (Copa et al.), titled “Devices, Systems, and Related Methodsfor Delivery of Fluid to Tissue”, the entire disclosures of which areincorporated herein by reference.

Another issue that can be encountered with these fluid delivery systemsis that a specific configuration of a system may not be adaptable oradjustable for use with multiple fluids having differing materialproperties, such as viscosity. In particular, these existing systems canoften include long tubular components through which fluid needs totravel, such as one or more elongated lumens or catheters, and fluidswith different viscosities can react differently to the resistance andfriction encountered when moving through fluid tubular components. Dueto this resistance, a fluid with a particular viscosity may exit thedistal delivery end of an injection orifice with a significantlydifferent amount of pressure or force than a fluid having a differentviscosity when using the same injection pressure. If the exit force ofthe fluid is too high or low, the fluid administration at the treatmentsite may be ineffective. In addition, differences in the mechanicalfeatures of the system may contribute to or cause reduced or enhanceddelivery pressure and/or fluid delivery velocity.

Due to the widely varied system and fluid requirements associated withthe delivery of therapeutic compositions to treatment locations in apatient, there is a need to provide improved procedures, systems, andcomponents for fluid delivery. Such procedures, systems, and componentswould provide for accurate and controlled dispensing of therapeuticcompositions to specific treatment locations within a patient, andfurther would compensate for different fluid properties, such asviscosity.

SUMMARY

The invention generally involves needleless fluid injection devices,systems, and methods. These devices and systems allow for targeteddelivery of therapeutic fluids at desired anatomical tissue locations,such as locations in the male or female urinary tract, (e.g., bladder,bladder neck, kidney, ureters, urethra, prostate, etc.).

The therapeutic fluids can include biologically active species andagents such as chemical and biochemical agents, for example. Exemplarydevices can be designed to deliver fluid at various tissue locations,and can further deliver multiple different therapeutic fluids havingvarying material properties (e.g., viscosity). The devices can becapable of delivering precise amounts of fluid for injection at preciselocations and at specific pressures that are adjustable depending on thefluid being administered to the location in the patient.

In one aspect of the invention, a needleless injection system isprovided to deliver therapeutic fluids to an internal treatment site ina patient, where the system is pressurized and is capable ofcompensating for differences in injection media viscosity and mechanicalsystem characteristics.

In another aspect of the invention, a needleless therapeutic fluidinjection system is provided, which generally comprises an injectionchamber and an applicator lumen. The injection chamber can include oneor more sensors that detect the data used to determine the flow rate ofan injection fluid or injectate. These sensors can be located on aninjection cylinder of the injection chamber, for example. The sensorscan detect a speed at which a plunger of the system moves when thesystem is being primed or run through a test cycle using a predeterminedpressure. Data received from the sensors can then be used by amicroprocessor-based control system to calculate the flow rate of theinjection fluid, wherein the control system may be located within aconsole. This flow rate can then be used to calculate the injectionpressure required to achieve a specified injection depth and/or velocityfor that fluid exiting the system.

In another aspect of the invention, a method is provided for deliveringa therapeutic fluid using a needleless fluid delivery system. The methodgenerally comprises providing a needleless fluid delivery system havinga minimally invasive access device (e.g., a shaft or catheter tube), aninjection chamber, and an injector assembly or console. The method canalso include accessing a treatment location with the minimally invasiveaccess device, infusing injection media into the fluid delivery systemat a set or predetermined pressure, measuring the flow rate of the fluidwith at least one sensor, which may be incorporated into the console orinjector assembly, determining the injection pressure based upon theflow rate required to achieve the desired injection depth, and adjustingthe injection pressure until the desired injection depth for the fluidexiting the access device or shaft is achieved.

In another aspect of the invention, the assessment of flow rate willtake place before the treatment location is accessed by the device. Itis further noted that the injection pressure can then be adjusted afterthe desired depth is achieved. The pressure will be adjusted based onthese measurements to achieve an equivalent scale of user-controlled“injection power” versus fluid or jet speed.

In another aspect of the invention, a method is provided forcompensating for variability in a pressurized drug injection system. Themethod comprises providing a needleless fluid delivery system having aminimally invasive access device (e.g., a shaft or catheter tube), aninjection chamber, and an injector assembly or console. The method canalso include accessing a treatment location with the minimally invasiveaccess device, infusing injection media into the fluid delivery systemat a set injection speed, measuring the pressure with at least onesensor that is incorporated into the console or injector assembly,determining the injection pressure based upon the flow rate required toachieve the desired injection depth, and maintaining the pressure sothat the desired injection depth is achieved.

In another aspect of the invention, a needleless therapeutic fluidinjection system is provided that includes modular, interchangeablecomponents. In particular, the system can comprise a console thatgenerally includes the electronic and/or pneumatic control componentsfor the system, an injection chamber, and a shaft or catheter tube. Theconsole and injection chamber are functionally attached in such a waythat the console can control the pressure that is generated in theinjection chamber for fluid administration at the distal end of theshaft or catheter tube. The injection chamber comprises a syringe-typestructure, where the movement of a plunger of the syringe is controlledby the console. However, the injection chamber can be disconnected fromthe console, and the injection chamber and its attached catheter tubecan be discarded, if desired. Notably, the fluid contained within theinjection chamber does not come in contact with any portion of theconsole, therefore, the console is reusable for multiple cycles simplyby attaching and detaching different injection chambers. Further, theproximal end of the shaft or catheter tube may be either detachably orpermanently connected to the injection chamber.

In another embodiment of the invention a test sequence is used toestablish the operating parameters for a fluid injection system of thetypes described herein. In particular, this test sequence can be used toadjust the operating parameters of the system to compensate fordifferent fluid viscosities. The test sequence involves using areference fluid, such as water, which is provided to the system in theinjection chamber. The reference fluid is then pressurized and dispersedfrom the distal end of the catheter tube. During this process, sensorsthat determine how fast the fluid moves when subjected to a certainamount of pressure can take one or more measurements. A therapeuticfluid can then be provided to the injection chamber, where it is alsopressurized and dispensed from the distal end of the catheter tube,while speed measurements are again taken by the sensors. Themeasurements can be taken at a relatively low pneumatic pressure andalso at a relatively high pneumatic pressure, along with intermediatepressures, if desired, and these measurements are compared to thecharacteristics of the reference fluid. The console can then becalibrated to compensate for the fluid viscosity of the therapeuticfluid.

In another aspect of the invention, the viscosities of both a referencefluid and a therapeutic fluid are known, such that a method involvestesting the system with the reference fluid to characterize the actualdevice being used, then the device is drained of the reference fluid.The pressure scale is then adjusted based on the performance of theparticular device and the viscosity of the therapeutic fluid. At thispoint, the therapeutic fluid can be loaded and injected. In this way,therapeutic fluid is conserved. In order to interpret the data points ofjet speed versus pressure for given device and find the pressure neededfor the desired speed, the following equations can be used:

$v_{jet} = {\frac{v_{plunger}A_{{inj}.{cham}.{bore}}}{N_{orifices}A_{jet}} = \frac{Q_{total}}{N_{orifices}A_{jet}}}$$v_{jet} \propto \sqrt{p_{injection}}$

To more generally determine the pressure where only the viscosity isknown and no calibration test is preformed, the Darcy-Weisbach Equationcan be used in conjunction with Bernoulli's Equation.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further explained with reference to theappended Figures, wherein like structure is referred to by like numeralsthroughout the several views, and wherein:

FIG. 1 is a schematic illustration of one embodiment of a needlelessfluid delivery system for delivering a therapeutic fluid to a treatmentlocation, in accordance with the invention;

FIG. 2 is a side view of an embodiment of a tube-like device of theinvention, which may be a non-metal, polymeric tube component;

FIG. 3 is a schematic illustration of an embodiment of a needlelessfluid delivery system of the invention, which is capable of adjustinginjection properties in response to certain fluid properties that areexhibited when delivering a therapeutic fluid to a treatment location ofa patient; and

FIG. 4 is a schematic illustration of an embodiment of a needlelessfluid delivery system of the invention, which is capable of adjustinginjection properties in response to certain fluid properties that areexhibited when delivering a therapeutic fluid to a treatment location ofa patient.

DETAILED DESCRIPTION

The invention relates to devices and methods useful for injecting fluidinto tissue for treatment. The fluid can be injected without the use ofa needle and can therefore be referred to as a needleless fluidinjection system. Needleless fluid injection systems of the inventioncan include one or more orifices that deliver fluid in the form of astream of fluid, which may be referred to as a jet or fluid stream, at apressure, velocity, and stream size that allow the fluid stream to passthrough a tissue surface, penetrate into the bulk of the tissue belowthe tissue surface, and become dispersed as fluid particles within thetissue, such as in the form of a cloud of dispersed fluid particles ordroplets, without a needle structure passing into the tissue. The typeof tissue injected for treatment can be any amenable tissue, which caninclude tissue at or near the urinary tract (e.g., tissue of theprostate, kidneys, ureters, urethral tissue, bladder (including thebladder neck), etc.), or other tissues such as heart tissue, as desired.

Needleless devices of the type described herein generally include adistal end and a proximal end. As used herein, a “distal end” of adevice or system refers to an end area or portion of the device orsystem that can be introduced internally within a patient's body duringa treatment procedure. For example, an elongate shaft or catheter of theneedleless injection systems of the invention generally include a distalend that is the first portion of the device that is introduced into thepatient for treatment. A distal end may include functional features thatoperate on fluid or tissue during use, such as one or more ejectionorifices, delivery heads (e.g., end effectors, nozzles, etc.) that houseone or more ejection orifices, a frictional tissue holding tip, tissuetensioners, lighting or other optical features, steering features, andthe like.

As used herein, a “proximal end” of an exemplary needleless device orsystem is the end that is opposite the distal end of that device orsystem. To that end, each component of a system can include its ownproximal and distal ends, while the overall system can also includeproximal and distal ends. For one example, a needleless fluid injectionsystem of the invention can include an injector body or console at aproximal end that remains external to the patient during use and anelongate shaft or catheter tube at a distal end. That is, exemplaryneedleless fluid delivery devices or systems can include a proximal endthat includes a console, and an elongate shaft extending from a proximalend, which is in communication with the console, to a distal end. One ormore injection orifices at the distal end can be in fluid communicationwith the console.

An exemplary console used with systems of the invention can include ahousing that connects to or is otherwise (directly or indirectly) influid communication with an elongate shaft. The console can includefluid that can be pressurized by a pressure source to cause the fluid toflow through the shaft for injection into tissue at the distal end. Adevice can eject fluid from one or multiple ejection orifices that canbe located at the distal end of the shaft.

Devices, systems, and methods are described herein that can be used toinject a fluid through a surface of a tissue, without the use of aneedle penetrating through the tissue surface and into the bulk of thetissue, and dispersing as particles or droplets within the tissue belowthe tissue surface. The injected fluids may be referred to as an“injectate” or “injection fluid”, which may be any type of fluid such asa therapeutic fluid. The injectate can be administered into tissue in aneedleless manner, whereby the injectate is delivered as a pressurizedfluid stream or jet. This contrasts with injections performed using aneedle, whereby a hollow needle structure penetrates tissue to locate ahollow end of the needle within a tissue mass, below the tissue surface,after which the needle carries fluid into the bulk of the tissue anddelivers the fluid at a relatively low pressure to the tissue in theform of a body or pool of fluid known as a bolus.

Referring now to the Figures, wherein the components are labeled withlike numerals throughout the several Figures, and initially to FIG. 1,one preferred configuration of a needleless fluid delivery system 100 isillustrated. Delivery system 100 generally includes an injection consoleor console 102, an injection chamber 108, and a catheter tube orelongate shaft 104. The console 102 includes a user interface 106, whichcan be used for activating and controlling the activities of the variouscomponents of the delivery system 100. The user interface 106 caninclude an input means for selectively delivering a pressurized fluidthrough the injection chamber 108. The user interface 106 may furtherinclude one or more actuatable devices, such as a foot petal 107 (asshown), a hand activated controller, switches, buttons, and/or the like.It is also contemplated that the user interface 106 can include atouch-screen that is capable of receiving touch commands and mayoptionally include a display system for displaying information such asthe mode of operation that is being used and/or certain operatingparameters of the system.

Although console 108 can include a wide variety of features, any consoleused in the fluid delivery systems of the invention can generallyinclude a housing, a pressure chamber, and a pressure source. A consolecan have any configuration, size, or design, ranging from a small,hand-held design to a relatively larger floor or table-mounted console.The consoles can also include separate or separable components such as apressure chamber or injection chamber that can be attached, used for aninjection procedure, and detached and optionally discarded or sterilizedand reused. A shaft or catheter tube can also be attached to a consoleor a pressure chamber in a manner that facilitates separation andoptional re-attachment or disposal. With separable components, a shaftor injection chamber can be attached to a console housing and used toinject a first patient and/or a first injectate, and then the shaft orpressure chamber can be removed and discarded or sterilized. A secondshaft or pressure chamber can then be attached to the console to treat asecond patient or the first patient with second injectate or administeranother treatment of the first injectate. The second patient orinjectate can involve injection and treatment of the same type of tissueas the first patient or injectate, or of a new type of tissue than wastreated in the first treatment. In this manner, separable and optionallydisposable shaft or pressure chamber components of a needlelessinjection system can allow a console housing to be used multiple timesto inject the same or different injectates to the same or differentpatients, and to the same or different types of body tissue, therebyproviding an injection system that is flexible for use in a wide varietyof situations and with a wide variety of fluids.

A console can further include actuating features to control distal endfeatures of the system, such as for steering a steerable distal end of asteerable shaft or catheter tube or to actuate ejection of fluid(control fluid or injection fluid). A console can further includeactuating features to move a moveable or extendable injection shaft orone or more injection orifices or control orifices relative to anothershaft component such as a working shaft. A console can further includeoptional ports to connect a console housing to auxiliary devices,electronics (e.g., control systems), and optical features such as alens, fiber optic, or electronic viewing mechanism. One or moreattachment ports can optionally attach a console to an external andoptionally remote component such as an external or remote pressuresource, vacuum source, or an external or remote fluid reservoir tosupply injectate or control fluid. For example, a console housing mayhave a fluid port that attaches to a source of a fluid (e.g., injectateor control fluid), to supply the fluid to the console housing, such asto a permanent or detachable pressure chamber. The console can include apressure chamber and a pressure source capable of pressurizing a fluidcontained in the pressure chamber to cause the fluid to flow from theconsole, through a lumen in the shaft, and then through an ejectionorifice as either injectate or a control fluid.

In embodiments of devices that involve the use of a control fluid, apressurized control fluid can be produced by a console using any usefultechnique and mechanism. For example, the pressurized control fluid canbe produced by a pressure source, such as any pressurized fluid source,magnetohydrodynamic power, expanding steam or gas power, or the like,with any available and useful control fluid, which may be a liquid or agas.

The injection chamber 108 can include a surface opening 109, which canprovide an opening through which a sensor can detect a plunger or detectwhen it has reached a certain point (e.g., to gauge its speed), forexample, and a therapeutic fluid supply 110. Fluid supply 110 can beprovided as a syringe that is manually activated, such as by physicallypressing a plunger into a syringe barrel that is at least partiallyfilled with fluid to push fluid from the syringe barrel. Alternatively,fluid supply 110 can be automatically or mechanically activated, such aswith an electronic fluid supply controller or with one or more remoteactivation devices that can be manipulated by the user to move theplunger into and out of a syringe barrel. In yet another alternative,the fluid supply 110 is not a syringe, but instead includes a largerfluid source, such as a reservoir or other container that holds thefluid until it is provided to the injection chamber 108. Such acontainer can be positioned so that the fluid is gravity fed to theinjection chamber, for example, or so that the fluid can be extractedusing a vacuum source, for another example. With any of the differenttypes of fluid supplies used with the systems of the invention, it iscontemplated that an exact amount of fluid to be administered can bepremeasured and provided to the system until that quantity of fluid isdepleted and/or a predetermined amount of fluid can be extracted from arelatively large fluid supply.

A fluid chamber can be a space or volume at a proximal end of a device,such as at a console housing, that can be used to contain pressurized ornon-pressurized fluid (e.g., control fluid or injectate). Examples ofspecific types of fluid chambers include fluid reservoirs and pressurechambers. Optionally, a proximal end of a device may include one ormultiple fluid reservoirs and pressure chambers, which can be providedfor one or more different fluids including one or more injectates, oneor more control fluids, or combinations of injectates and controlfluids.

A fluid reservoir is generally a type of fluid chamber that can containa fluid for a purpose of containing, transferring, holding, or storing afluid, such as a fixed volume fluid chamber, and may be included as apermanent or removable (i.e., attachable and detachable) component of aconsole housing.

A pressure chamber or injection chamber can be a type of fluid chamberfor containing one or more fluids (e.g., control fluid or injectate) fora purpose of placing the fluid under pressure to deliver the fluidthrough a lumen to a distal end of a shaft for ejection from an ejectionorifice. Examples of pressure chambers include a syringe chamber andother variable volume spaces that can be used to contain and pressurizea fluid. Examples of variable volume pressure chambers include spacesthat can exhibit a variable volume for increasing or decreasing thevolume (and correspondingly decreasing or increasing pressure) withinthe variable volume chamber space. Such pressure chambers can include aplunger, piston, bellows, or other mechanisms. A pressure chamber can bepressurized by a pressure source attached to the plunger, bellows, orpiston, etc., such that fluid contained in the pressure chamber isejected under pressure. This pressurized fluid can be used for priming adevice and/or for ejecting fluid from an ejection orifice for injectionand/or to produce a control force, for example. A pressure source may beany source of energy (e.g., mechanical, electrical, hydraulicallyderived, pneumatically derived, or the like) such as a spring, solenoid,compressed air, manual syringe, electric power, hydraulic, pneumaticpressure sources, or the like. A pressure chamber may be a permanent orremovable (i.e., attachable and detachable) component of a consolehousing.

Referring again to FIG. 1, a proximal or supply end 111 of the cathetertube or shaft 104 extends from a distal end of the injection chamber108. The catheter tube 104 may be permanently attached or connected tothe injection chamber 108 so that the tube 104 and chamber 108 areprovided to the system either as a single component. Alternatively,catheter tube 104 may be attachable and detachable from injectionchamber 108, such as with quick connection fittings, so that theinjection chamber 108 and tube 104 are provided to the system asseparate components. Catheter tube 104 further includes a delivery ordistal end 112, which is generally opposite the proximal or supply end111.

Catheter tube or shaft 104 is a generally continuous, elongated tube,which may include multiple lumens, attachments, or other components thatmay extend along all or part of the length of the tube 104. Cathetertube 104 may further comprise a number of different configurations, suchas an endoscope or other catheter configuration, for example.Alternatively, catheter tube 104 can comprise a flexible tube 114 toallow for easy positioning of the delivery or distal end 112 within thepatient. Supply or proximal end 111 of the tube 104 can be generallyconfigured to attach to the injection chamber 108 and can include aquick-connect style connector, which is schematically illustrated asconnector 116. One example of a type of connection that can be usedincludes compression fittings, although any type of connector can beused that provides a secure engagement between components.

Delivery or distal end 112 can comprise a number of differentconfigurations, which can be selected to provide treatment to a certainlocation in the patient's body (e.g., a rectal treatment location, agastrointestinal treatment location, a nasal treatment location, abronchial treatment location, or an esophageal treatment location). Theconfiguration of this distal end 112 is designed and/or selected toprovide different types of treatment, such as can be provided byend-fire applicators or side-fire applicators. Further, in someembodiments, the catheter tube 104 can include an application specificapplicator, such as applicator 118, which in turn includes a fluidadministration port 120.

Examples of injection shaft configurations, features and combinations ofshaft features that can be useful according to the present descriptionare identified as U.S. Patent Application Publication No. 2006/0129125and U.S. Ser. No. 12/087,231, filed Jun. 27, 2008 (Copa et al.), titled“Devices, Systems, and Related Methods for Delivery of Fluid to Tissue”;and in Assignee's copending patent application titled “Devices, Systems,and Related Methods for Delivery of Fluid to Tissue”, by Crank, filed oneven date herewith, attorney docket number AMS0170/WO; and in Assignee'scopending patent application titled “Needleless Injection DeviceComponents, Systems, and Methods”, by Crank, filed on even dateherewith, attorney docket number AMS00171/WO, which are all incorporatedherein by reference.

In another aspect of the invention, in communication with a proximal endof a device is an elongate shaft that extends from the proximal end(i.e., from a proximal shaft end), that is optionally removablyconnected to the console (or a component of the console such as aremovable pressure chamber), to a distal end that can be placed in apatient during an injection procedure. A shaft can be of variousdesigns, minimally including an injection lumen to carry injectate froma proximal end of the device to a distal end of the shaft. A usefulshaft may optionally include at least one separate lumen for carryingcontrol fluid to a distal end.

An injection shaft minimally includes an injection lumen incommunication with an injection orifice. The injection shaft can includestructure such as sidewalls that define the injection lumen, thesidewalls being of sufficient strength to withstand operating pressuresused to deliver injectate from the injection orifice at an elevatedpressure sufficient to cause the injectate to be ejected from theinjection orifice to penetrate a tissue surface and become injected andinto and dispersed below the tissue surface. An injection shaft may beconstructed of a flexible material (e.g., a metal or polymeric tube) andmay be prepared from exemplary materials capable of withstandingpressure of an injection, e.g., nitinol, stainless steel, reinforced(e.g., braided) polymer.

A basic version of an injection shaft of a device as described can be an“injection shaft” that includes a proximal end, a distal end, and asidewall that defines an internal lumen (“injection lumen”), and atleast one injection orifice at the distal end in connection with theinjection lumen. An injection shaft can optionally include multipleinjection orifices, optionally one or more control orifices at thedistal end, and optionally a control lumen extending from the proximalend to the optional control orifice.

An injection shaft can be any elongate structure capable of deliveringfluid to a distal end of a shaft at a pressure suitable to injecttissue, as described. Exemplary injection shaft structures includerelatively flexible hollow bodies having a distal end, a proximal end,sidewalls extending between the ends, an internal lumen (“injectionlumen”) defined by interior surfaces of the sidewall. The injectionlumen is in communication with one or more injection orifices at thedistal end. The injection orifices may include a member of differentconfigurations, such as an aperture or bore in an injection shaftsidewall, an aperture or bore in a nozzle, end effector, injection head,or other structure in communication with the injection lumen.

Referring now to FIG. 2, a portion of one exemplary catheter tube 104 isillustrated, which can include a non-metal, polymeric tube material 200that has a proximal attachment end 202 and a distal treatment end 204.Tube 200 has a tube length 206 that corresponds generally to the type oftreatment being performed on the patient. In other words, the tubelength 206 is chosen to correspond with the location of the body towhich the distal treatment 204 needs to be positioned and the type oftreatment being performed to treat a particular area of the body. Forexample, when the device 200 is configured for use for performing acytoscopic or endoscopic procedure, the tube length 206 can range fromabout 18 inches to about 72 inches in length, although it iscontemplated that the tube 104 can be longer or shorter than this range.The tube 200 may be made of a wide variety of materials and combinationsof materials, such as NiTi, Polyetheretherketone (PEEK), PEI, PI,braided polymers, stainless steel, and the like.

When fluid flows through the inner portion of the catheter tube 104 fora treatment procedure, it will be subjected to a certain amount ofresistance caused by its contact with the inner walls of tube 104. Theamount of resistance will be greater for relatively long tube lengthsand relatively small tube inner diameters, and should be taken intoconsideration when calculating or determining the desiredcharacteristics that the fluid will have when it reaches the distal ordelivery end of the tube. In addition, the amount of resistance willfurther be impacted by the fluid chosen to be administered by the system100. In particular, the fluid viscosity correlates to the amount ofresistance that is experienced by the fluid. In addition, variousmechanical characteristics of an injection system may affect thepressure of fluid flowing through the system, such as surface roughness,mechanical obstructions to straight fluid flow (e.g., elbows or bends inthe fluid path), and/or other obstructions to fluid flow.

To account for these differences in the injection systems and injectionfluids, a needleless fluid delivery system 240 of the type illustratedin FIG. 3 can be used. This system 240 includes one or more sensors 250that are used for detecting data and to determine the flow rate of theinjection media being used. The sensors may include, for example,pressure sensors, strain gauges, optical sensors, Hall Effect sensors,magnetic sensors, linear voltage displacement transducers, inductancetransducers, capacitance sensors, and/or the like. The sensors 250 canbe located on an injection cylinder 252 of the injection chamber 108,for example. The sensors 250 can detect the speed of the plunger duringa test cycle for the needleless fluid delivery system 240. This plungerspeed is measured at a set or constant predetermined pressure. Plungerspeed data obtained by the sensors 250 is used by a computer controlsystem for an injector 103 of the injector console 102 to calculate theflow rate. This flow rate is then used to calculate the injectionpressure required to achieve a specific injection depth for the fluid atthe distal end of the catheter tube. Using the sensors in this way canreduce the variability in injection depths achieved when using differentfluids with certain pressurized injection systems.

In accordance with the invention, a method of compensating for systemvariability and injection media variability in a pressurized druginjection system is provided. This method includes the step of providinga needleless fluid delivery system that includes a minimally invasiveaccess device, such as an elongated shaft or catheter tube, an injectionchamber, and a console. The method also includes the step of accessing atreatment location with the minimally invasive access device, infusinginjection fluid into the fluid delivery system at a set pressure,measuring the flow rate with at least one sensor that is incorporatedinto the injection assembly, determining the injection pressure basedupon the flow rate that is required to achieve a desired depth ofinjection at the distal end of the device, and adjusting the pressureuntil the desired depth of injection is achieved. In one embodiment, theinjection pressure versus speed calibration is performed beforeaccessing the treatment area.

Another embodiment of the invention includes a needleless injectionsystem 300, as is illustrated in FIG. 4. This system 300 includes afirst sensor 301 that is positioned on the injection chamber 108 andused to detect a pressure, and a second component 302 that is alsopositioned on the injection chamber 108 and is used for delivering fluidat a set injection speed. Rather than measuring the flow rate via theplunger speed at a set injection pressure, this injection system 300 isused to determine the flow characteristics of a particular fluid bymeasuring the pressure at a set injection speed. In this way, the systemis capable of compensating for variability in a pressurized druginjection system. The method used includes the steps of providing aneedleless fluid delivery system having a minimally invasive accessdevice or catheter tube, an injection chamber, and an injector console.The method further includes the steps of accessing a treatment locationwith the minimally invasive access device, infusing injection media intothe fluid delivery system at a set injection speed, measuring thepressure with at least one sensor that is incorporated into theinjection device, determining the pressure of the fluid based upon theflow rate required to achieve the desired injection depth, andmaintaining the pressure so that the desired depth of fluid injectioncan be achieved.

In another embodiment of the invention, a test sequence is used toestablish the operating parameters for a fluid injection system of thetypes described herein. In particular, this test sequence can be used toadjust the operating parameters of the system to compensate fordifferent fluid viscosities. The test sequence involves using areference fluid, such as water, which is provided to the system in theinjection chamber. The reference fluid is then pressurized and dispersedor administered from the distal end of the catheter tube. During thisprocess, measurements are taken by sensors that determine how fast thefluid is moving when subjected to a certain amount of pressure. A testportion of a particular therapeutic fluid can then be provided to theinjection chamber, where it is also pressurized and dispensed from thedistal end of the catheter tube, while speed measurements are taken bythe sensors. The measurements can be taken at a relatively low pneumaticpressure and also at a relatively high pneumatic pressure, along withintermediate pressures, if desired, and these measurements are comparedto the characteristics of the reference fluid. The console can then becalibrated to compensate for the fluid viscosity of the therapeuticfluid. As set out above, however, in one aspect of the invention, theassessment of flow rate will take place before the treatment location isaccessed by the device, etc. In yet another embodiment of the invention,the delivery system includes an injection console and a catheter tube,along with a manually activated syringe.

The needleless therapeutic fluid delivery systems of the invention canbe used by medical professionals in combination with a medical imagingsystem such as a computer axial tomography (CAT) system, a magneticresonance imaging (MRI) system, or a transrectal ultrasound (TRUS)system (used in the case of treating a prostate gland), for example.Through the use of such a medical imaging system, the medicalprofessional can verify the location of the delivery or distal end ofthe system for proper insertion thereof relative to the desiredtreatment location.

The present invention has now been described with reference to severalembodiments thereof. The entire disclosure of any patent or patentapplication identified herein is hereby incorporated by reference. Theforegoing detailed description and examples have been given for clarityof understanding only. No unnecessary limitations are to be understoodtherefrom. It will be apparent to those skilled in the art that manychanges can be made in the embodiments described without departing fromthe scope of the invention. Thus, the scope of the present inventionshould not be limited to the structures described herein, but only bythe structures described by the language of the claims and theequivalents of those structures.

1. An injection system for delivering at least one fluid to a treatmentsite, wherein the system is pressurized and is adjustable to compensatefor differences in fluid viscosity.
 2. The injection system of claim 1,wherein the injection system comprises a needleless injection device. 3.The injection system of claim 2, wherein the needleless injection devicecomprises a console, an injection chamber, and an elongate shaft havinga distal end.
 4. The injection system of claim 3, wherein the distal endof the shaft comprises at least one injection orifice, wherein at leastone fluid is ejectable under pressure from the at least one injectionorifice.
 5. (canceled)
 6. A needleless injection system comprising: aninjection chamber comprising at least one sensor; and an applicatorlumen extending from a distal end of the injection chamber; wherein theat least one sensor is capable of detecting at least one property of theflow of an injection fluid that is contained within the injectionchamber.
 7. The needleless injection system of claim 6, wherein theinjection chamber further comprises an injection cylinder, and whereinthe at least one sensor is positioned for communication with theinjection cylinder.
 8. The needleless injection system of claim 6,wherein the injection chamber further comprises a plunger positioned forslideable movement within the injection cylinder, and wherein a speed ofmovement of the plunger relative to the injection cylinder is detectableby the at least one sensor.
 9. The needleless injection system of claim6, further comprising a control system, wherein data detected by the atleast one sensor is transferable to the control system for calculationof the flow rate of the injection fluid.
 10. (canceled)
 11. A method ofdetermining a flow rate of a fluid in a needleless injection system,wherein the system comprises: a control system, an injection chambercomprising an injection cylinder, a plunger positioned for slideablemovement within the injection cylinder, and at least one sensor; and aninjection shaft, wherein the at least one sensor is capable of detectingat least one property of the flow of an injection fluid, the methodcomprising the steps of: providing a first fluid to the injectionchamber; pressurizing the first fluid to a first pressure; moving theplunger relative to the injection chamber and evacuating at least aportion of the first fluid from the injection chamber while detecting afirst speed of the plunger with the at least one sensor; providing thefirst speed of the plunger detected by the at least one sensor to thecontrol system; calculating the flow rate of the first fluid.
 12. Themethod of claim 11, further comprising the steps of: using the flow rateof the first fluid to calculate an injection pressure required toachieve a predetermined velocity for a second fluid.
 13. The method ofclaim 12, wherein the first fluid has a different viscosity than aviscosity of the second fluid.
 14. The method of claim 12, wherein thefirst fluid comprises at least one material property that is differentfrom that material property of the second fluid.
 15. The method of claim11, further comprising the steps of: providing a second fluid to theinjection chamber; pressurizing the second fluid to a second pressure;moving the plunger relative to the injection chamber and evacuating atleast a portion of the second fluid from the injection chamber whiledetecting a second speed of the plunger with the at least one sensor;providing the second speed of the plunger detected by the at least onesensor to the control system; calculating the flow rate of the secondfluid.
 16. The method of claim 15, further comprising the step ofcomparing the flow rate of the first fluid to the flow rate of thesecond fluid.
 17. A method of delivering fluid, comprising the steps of:providing a needleless fluid delivery system comprising a console, aninjection chamber operatively connected to the console, and a cathetertube extending at a proximal end from the injection chamber; providing afirst fluid to the injection chamber; pressurizing the injection chamberto a first pressure to cause the first fluid to move from the injectionchamber to the distal end of the catheter tube; measuring the flow rateof the first fluid with at least one sensor as the first fluid movesfrom the injection chamber to the distal end of the catheter tube;determining an injection pressure of the first fluid based on a flowrate required to achieve a desired injection depth for the first fluid;adjusting the injection pressure of the first fluid until a desiredsetting for the first fluid is achieved; and accessing a treatmentlocation with a distal end of the catheter tube.
 18. The needlelessinjection system of claims 23, wherein the injection chamber isremoveably attached to the console.
 19. The needleless injection systemof claim 18, wherein the injection chamber further comprises a plungerthat is moveable within the injection cylinder in response to pressurechanges within the injection cylinder.
 20. (canceled)
 21. The needlelessinjection system of claim 19, further comprising a quantity of fluidwithin the injection chamber, wherein the fluid within the injectionchamber is isolated from the control components of the console. 22.(canceled)
 23. A needleless injection system comprising: a consolecomprising control components for the system; an injection chamberremoveably attached to the console; and a first injection shaft attachedat a proximal end to the injection chamber for fluid communication withan injection cylinder of the injection chamber; wherein the consolecontrols the pressure that is generated in the injection chamber forfluid administration at a distal end of the injection shaft.
 24. Theinjection system of claim 23, wherein the first injection shaft isremoveably attached to the injection chamber.
 25. The injection systemof claim 24 in combination with at least a second injection shaft thatis removeably attachable to the injection chamber after detaching thefirst injection shaft.
 26. The injection system of claim 25, wherein thefirst and second injection shafts comprise different distal endfeatures.